Ammonium nitrate explosive composition



finite 1 AMIVIONIUM NITRATE EXPLOSIVE COMPOSITION N Drawing. Filed Feb. 2, 1959, Ser. No. 790,364

Claims. (Cl. 52-14) This invention is concerned with novel compositions of matter for use as explosives, intermediate compositions useful in preparing the explosive compositions, and methods of preparing both the intermediate and ultimate explosive compositions. It is also concerned with a novel process of producing a high order explosion.

Since the issuance of US. Patent No. 2,703,528 to Lee and Akre, the mining industry has had the advantage of lower costs for explosives through use of the process disclosed therein which enabled low cost ammonium nitrate to be substituted for a major portion of the high cost dynamites previously required in the mining art. Materials such as trinitroglycerin, dinitroglycerin and nitrotoluenes were included in the ammonium nitrate to render the composition sensitive to detonation by a blasting cap.

Subsequently, various other mixtures of ammonium nitrate were oifered to the mining industry for use as explosives. Initially, these consisted of simple mixtures of ammonium nitrate and a carbonaceous material such as carbon black, coal fines or coke breezes to lower the cost of the explosive, reduce its cap sensitivity and enhance its safe handling characteristics. Such compositions contained about 4% to 6% carbonaceous material with the balance ammonium nitrate containing 2% Y isuniformly available to such oxygen, propagation of the explosion throughout the column takes place. If there is surplus carbonaceous material available, the initial explosion does not propagate itself and, unless there is additional reaction supplied by a primer charge, a very low order detonation takes place. If there is a deficiencyof carbonaceous material there will be an excess of oxygen and the explosion will not propagate itself.

Assuming that the detonant has created the decomposition as shown in the above equation, the role of the carbonaceous additive is a simple one. Under the conditions of temperature and pressure imposed by the detonating force, a simultaneous reaction takes place between the carbonaceous material and oxygen released by the ammonium nitrate. This sets the stage for propagation of the explosion through the column. The complex reaction raises the temperature, producing still higher pressure and greater gas expansion.

More recently liquid hydrocarbons such as diesel oil or fuel oil have been used wholly or in part as the carbonaceous material. In actual practice, ammonium nitrate prills containing 2% to 3% diatomaceous earth drains i atent i in paper or polyethylene bags is shipped to the point of use. Fuel oil is then added to the individual sack or in bulk mixing equipment. Such compositions generally have been adapted as preferable although some segregation of oil occurred and the particles of ammonium nitrate were oily to the touch.

When ammonium nitrate prills are treated with fuel oil according to the prior art, it is believed that the circumference or outer shell of the prill has an excess, and the interior a deficiency, of fuel oil, so that as each prill decomposes during detonation there is only a very brief time when there is proper oxygen and carbon bal ance so as to produce an explosion capable of propagating itself. This balance is so brief, generally, that the explosion is unable to propagate itself. For this reason, it is necessary with such prior art mixtures to use a high explosive primer in conjunction therewith. The primers aid in the detonation of the entire mass by providing the additional necessary energy that did not come from the ammonium nitrate because of the poor oxygencarbon balance.

Uniform distribution of the carbonaceous material throughout the mass and throughout each individual prill aids in obtaining this balance. Aging the ammonium nitrate-fuel oil mixture permits more uniform distribution of the oil in the prills but during aging excessive caking takes place. Caking of the mixture interferes with its utilization since a free flowing material is necessary for most applications. Even if such a mixture could be aged without caking it would be an additional expense, inconvenience and danger to do so, and the resultant ammonium nitrate-fuel oil mixture would still require a powerful primer.

A major disadvantage with mixtures of ammonium nitrate and a carbonaceous material, either solid or a liquid hydrocarbon, is that they are difiicult to detonate with a blasting cap and detonating fuse. To obtain complete first order detonation of such ammonium nitrate mixtures it was necessary to use high explosive primers, such as dynamite or nitroglycerin, usually attached to a line of detonating fuse. The use of such primers as an explosive adjunct decreased the personnel safety factor, raised labor and material costs and increased the complexity of loading a hole in preparation for shooting. The cost was increased greatest for small size holes since, as the diameter of the mass of ammonium nitrate mixture decreased, the weight ratio of high explosive primer to mixture necessary to obtain a first order detonation increased from approximately 1:10 for a nine inch diameter to about 1:3 for a two inch diameter.

The explosive compositions of the present invention overcome these difficulties of the prior art by providing non-cap-sensitive explosive compositions which are economical in direct materials cost, easier to load in the hole and are detonatable by a single line of detonating fuse and blasting cap to a first order detonation without the attendant cost and hazard of using dynamite or other high explosive primers. Other advantages will be apparent as this disclosure continues.

It has been discovered that the addition of a small quantity of a salt, such as an alkali metal (sodium) or ammonium salt, of dior tri-sulfonic acids of pararosaniline or rosaniline, or mixtures thereof, or a small quantity of sulfonates of monoand/or di-methyl naphthalenes, or a small quantity of mixtures of both of these classes of sulfonates, to ammonium nitrate produces valuable explosive intermediates.

A mixture of sulfonates of mono and dimethyl naphthalenes is sold under the name Petro Ag while the commercial material Acid Magenta is a convenient source of the sulfonates of pararosaniline and rosaniline.

The intermediates are not explosive, but can be readied Patented Mar. 14, 1961 for use as explosives simply by adding a liquid hydrocarbon such as fuel oil to the mixture in the proper amount. The explosives so produced have the advantage in that they can be detonated to a first order explosion simply by the use of a detonating fuse and blasting cap, Without the need of an expensive or dangerous high explosive primer.

Fuel oil added to the ammonium nitrate treated with a small quantity of mixtures of salts, such as the sodium or ammonium salts, of dior tri-sulfonic acids of pararosaniline or rosaniline or a small quantity of sulfonates of mono or dimethyl naphthalenes, or a small quantity of mixtures of .both classes of such compounds, is rapidly and uniformly distributed through the entire prills of ammonium nitrate. This uniform distribution results in a subsequent balanced explosion which propagates as desired without the use of high explosive primers.

In a particular embodiment of the invention, ammonium nitrate in the form of uncoated prills approximately three-sixteenths of an inch in diameter is coated with approximately 0.025 to 0.1% of at least one of the aforementioned sulfonates or. a combination thereof. This intermediate mixture is not sensitive to detonation by a No. 8 blasting cap, which is the test used by the Bureau of Explosives to determine whether or not a compound is cap sensitive. After such treatment, the ammonium nitrate-sulfonate mixture is ready for mixing with a suitable liquid hydrocarbon such as fuel oil and use as an explosive. Addition of the fuel oil, however, is advisably made at the place of use of the explosive rather than at the place of manufacture of the ammoniurn nitrate-sulfonate mixture since shipment and packaging of the ammonium nitrate-sulfonate mixture is less expensive and more convenient than would be the case if the mixture containing fuel oil was shipped. Furthermore, the ammonium nitrate-sulfonaie mixture can be handled and shipped as a nonexplosive while the mixture containing oil is an explosive which is dangerous and more costly to ship.

The inclusion of up to 0.5% of diatomaceous earth based on the ammonium nitrate in the mixture aids in more evenly distributing the sulfonates through the prilled ammonium nitrate and a first order detonation can be achieved without the use of high explosive primers. The use of diatomaceous earth in quantities greater than 0.5% requires the use of high explosive primer to effect a detonation after mixture with fuel oil. Additional parting agent above 0.5%, such as up to the 3% in commercial ammonium nitrate, to prevent caking during the period of time that the prills would normally be stored before use is not required when the sulfonates are used to coat the individual prills. However, uniform distribution of the sulfonates in the ammonium nitrate is important because too great of a concenration of the sulfonates, and particularly of the naphthalenic compounds, at any point in the batch can have adverse effects on the storage characteristcs of the material. Mixing of the ammonium nitrate, sulfonate, and diatomaceous earth if added, is effected in any convenient mixing apparatus.

The explosive capacity of various combinations of material was evaluated according to the following test:

The mixtures having the compositions reported in Table I following were prepared as described above and placed in 4%" by 9% cylindrical paper food containers. Each sample tested contained 3% pounds of finished mixture. The samples were prepared 24 hours before use. Pentaerythritol nitrate detonating fuse was inserted into the center of the cylindrical container containing the explosive along its entire length. A No. 6 blasting cap with a safety fuse was attached to the detonating fuse. To determine cap sensitivity, a blasting cap with safey fuse attached was inserted into the center of the charge. All test explosions were unconfined free-air blasts. A numerical rating was given to each blast result based on visual observance, sound, resultant decomposiae'zaoae 5; tion, smoke, damage to container and crater effect accord to the following grades.

Rating Order and Magnitude of Blast High order; cap sensitive: essentially complete detonation.

High order: complete detonation.

Good order: complete detonation.

Fair order: essentially complete detonation.

Medium order: essentially complete detonation.

Low order.

Very low order: partial decomposition.

Very low order: vicinity of boosterscattered prills.

Essentially no decomposition; slight in vicinity of booster,

scattered prills.

N o decomposition.

TABLE -1 Test results Detonating Fuse, Sample Grains Rating P.E.T.N./

PP+4% F0 167 10+ PP-|-5% FO 167 10+ PP+6% FO 167 10+ U -4% F 75 7 -4% F 167 6 -5% F0 75 6+ 5% F0 167 5 -6% F0 75 6 -6% F0 167 5 -5.5% FO Cap 10+ 05% B- 167 4 05% B- 167 3 05% B- 167 2 05% B- Cap '10 05% B- 37. 5 8 05% B- 75 4 05% B- 112. 5 3 05% B- 150 2 05% B- 187 5 2 05% B- Cap 8 05% B- 37 5 4 05% B- 75 3 005% B 37 5 10 005% B 75 6 025% B 37 5 9 025% B 75 4 05% B- 37 5 8 05% B- 75 3 0.1% B- 37 5 3 .1% B- 75 2 0.1% B- Cap 8 05% A- 37. 5 8+ .05% A+5 57 75. 0 4 .025% B+.025% A-l- 0 37. 5 i 2 UP-.O% B+.025% A+5.5% F0 75. 0 2 UP-.05% B+.05% A+5.5% F0 37. 5 2 UP-.05% B+.05% A+5.5% FO 75.0 2 UP--.025% B+.025% A+5.5% FO Cap 10 p UP.025% B+.025% A+5.5% FO 37.5 6

UP.025% B+.O25% A+5.5% FO 75. 0 3+ UP 025% B+.025% AzNo E0 Cap 10 UI-.025% B+.025% A:N0 FO 112. 5 9 UP--.025% B+.025% A:No FO 187.5 8 UP--.05% B+.05% A:No FO Cap 10 UP--.05% B+.05% A:No FO 112. 5 9 UP--.05% B+.05% AtNo F0 187. 5 8

1 Aged one week after adding fuel oil.

PP: Partcd ammonium nitrate prills-3% diatomaceous earth coating.

UP: Unparted ammonium nitrate prills.

F0: No. 2 diesel fuel oil.

D.E.: Diatomaceous earth.

A: Sodium and ammonium salts of di and tri-sulphonic acids of pararosaline and rosaniline.

B: Sulphonates of mono and di-mcthy1 naphthalencs.

,As can be seen from the data, in no case is the ammonium nitrate explosive intermediate cap sensitive before fuel oil is added. It cannot be detonated by use of r detonating fuse to a first order detonation even after fuel oil has been added unless it has previously been treated with the described compounds.

Various changes and modifications of the invention can be made and, to the extent that such variations incorporate the spirit of this invention, they are intended to requiring the use of a high explosive primer consisting essentially of ammonium nitrate and a member of the group consisting of the sulfonates of mono and di-methyl naphthalenes in an amount of 0.025% to 0.1% by weight of the ammonium nitrate, and a hydrocarbon oil that is liquid at room temperature and pressure uniformly distributed over and in the ammonium nitrate in an amount from about 4% up to about 8% by Weight of the ammonium nitrate.

2. An explosive non-cap sensitive composition detonateable with a blasting cap and detonating fuse and without requiring the use of a high explosive primer consisting essentially of ammonium nitrate and a member of the group consisting of the sulfonates of monoand di-methyl naphthalenes in an amount of 0.025 to 0.1% by weight of the ammonium nitrate, and a hydrocarbon oil that is liquid at room temperature and pressure uniformly distributed over and in the ammonium nitrate in an amount from about 4% up to about 8%, and up to about 0.5% of diatomaceous earth, by weight of the ammonium nitrate.

3. An explosive non-cap sensitive composition detonateable with a blasting cap and detonating fuse without requiring the use of a high explosive primer consisting essentially of ammonium nitrate and a member of the group consisting of the sulfonates of monoand di-methyl naphthalenes in an amount of about 0.025 to 0.1% by weight of the ammonium nitrate, and fuel oil uniformly distributed over and in the ammonium nitrate in an amount from 4% to 8%, by weight of the ammonium nitrate.

4. An explosive non-cap sensitive composition detonateable with a blasting cap and detonating fuse without requiring the use of a high explosive primer consisting essentially of ammonium nitrate and a member of the group consisting of the sulfonates of monoand di-methyl naphthalenes in an amount of about 0.025 to 0.1% by weight of the ammonium nitrate, and diesel oil uniformly distributed over and in the ammonium nitrate in an amount from 4% to 8%, by weight of the ammonium nitrate.

5. The method of producing an explosion of the first order consisting essentially of thoroughly mixing ammonium nitrate and a member of the group consisting of the sulfonates of monoand di-methyl naphthalenes in an amount of about 0.025 to 0.1% by weight of the ammonium nitrate, to form an intermediate mixture, adding a hydrocarbon oil which is liquid at room temperature and pressure to the intermediate mixture in an amount of about 4% to 8% based upon the weight of the ammonium nitrate and sufiicient to combine with oxygen upon decomposition of the ammonium nitrate to form an explosive mixture; placing the explosive mixture in a place to be blasted and detonating the explosive mixture by a detonating fuse and cap Without the use of a high explosive primer.

6. The method of producing an explosion of the first order consisting essentially of thoroughly mixing ammonium nitrate and a member of the group consisting of the alkali metal and ammonium salts of the diand trisulfonic acids of pararosaniline and rosaniline in an amount of about 0.025 to 0.1% by weight of the ammonium nitrate, to form an intermediate mixture, adding 77 a hydrocarbon oil which is liquid at room temperature and pressure to the intermediate mixture in an amount of about 4% to 8% based upon the weight of the ammonium nitrate and sufficient to combine with oxygen upon decomposition of the amonium nitrate to form an explosive mixture, placing the explosive mixture in a place to be blasted and detonating the explosive mixture by a detonating fuse and cap without the use of a high explosive primer.

7. The process of claim 5 in which the liquid hydrocarbon is a member of the group consisting of fuel oil and diesel oil.

8. The process of claim 6 in which the liquid hydrocarbon is a member of the group consisting of fuel oil and diesel oil.

9. The process of claim 5 in which up to 0.5% of diatomaceous earth is included in the intermediate mixture.

10. A composition according ot claim 1 containing as an added ingredient a member of the group consisting of the alkali metal and ammonium salts of the diand trisulfonic acids of pararosaniline and rosaniline in an amount of 0.025 to 0.1% by weight of the ammonium nitrate, with the combined total weight of the naphthalene, pararosaniline and rosaniline ingredients being not more than 0.1% by weight of the ammonium nitrate.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN EXPLOSIVE NON-CAP SENSITIVE COMPOSITION DETONATEABLE WITH A BLASTISNG CAP AND DETONATING FUSE AND WITHOUT REQUIRING THE USE OF A HIGH EXPLOSIVE PRIMER CONSISTING ESSENTIALLY OF AMMONIUM NITRATE AND A MEMBER OF THE GROUP CONSISTINGG OF THE SULFONATES OF MONO AND DI-METHYL NAPHTHALENES IN A AMOUNT OF 0.025% TO 0.1% BY WEIGHT OF THE AMMONIUM NITRATE, AND A HYDROCARBON OIL THAT IS LIQUID AT ROOM TEMPERATURE AND SPRESSURE UNIFORMLY DISTRUBUTED OVER AND IN THE AMMONIUM NITRATE IN AN AMOUNT FROM ABOUT 4% UP TO ABOUT 8% BY WEIGHT OF THE AMMONIUM NITRATE. 